Chapter 19.6, Problem 8AYLO

Summary Introduction

To discuss:

The intrinsic rate of the SA node and the role of vagal tone in modifying this to produce a normal resting heart rate.

Introduction:

Most of the involuntary action in the human system is controlled by the autonomic nervous system, either by its sympathetic or parasympathetic nervous system. Even though the heartbeat falls under involuntary actions, initiation and conduction of the heartbeat is highly controlled by the sinoatrial node (SA), in the heart generally called as the pacemaker of the heart and not by the autonomic nervous system. The autonomic nervous system can only influence the heartbeat rate in terms of increasing or by decreasing its heartbeat speed as per the stress feedback from outside or inside the body.